NAMS 2002 Workshop - ICOM 2008

Drinking and Wastewater Applications IV – 5
Thursday July 17, 11:00 AM-11:30 AM, Honolulu/Kahuku
Study of an External MBR for Degradation of Endocrine Disrupter
17(alpha)-ethinylestradiol
L. Clouzot (Speaker), University of Aix-Marseille, France
B. Marrot, University of Aix-Marseille, France - benoit.marrot@univ-cezanne.fr
P. Doumenq, University of Aix-Marseille, France
N. Roche, University of Aix-Marseille, France
The xenobiotic 17±-ethinylestradiol (EE2), a common oral contraceptive
component, is an endocrine disrupter with fish feminization induced at
concentrations as low as 0.1 ng.L -1 . EE2 occurrence in the aquatic environment
(0.5-5 ng.L -1 ) is due to inefficient removal in municipal wastewater treatment
plants (WWTPs). EE2 biodegradation is achieved by nitrifying micro- organisms
(autotrophic biomass), characterized by slow growth. Therefore, EE2 removal
requires activated sludge (AS) with a high sludge retention time (SRT). However,
in WWTPs, there is often an incomplete separation of water and AS, resulting in
low biomass concentrations and low SRTs. Membrane bioreactors (MBRs), with
a complete physical retention of AS, are a promising solution to enhance EE2
degradation. During the past 10 years, an exponential increase in MBRs
research and literature has been observed worldwide. Membrane fouling is a key
issue that has slowed MBR technology commercialization; however, a significant
increase in the breadth of application areas is anticipated. The aim of this study
is to use MBR technology to improve EE2 elimination during municipal
wastewater treatment. First, nitrifying AS acclimation was developed to obtain a
specific biomass effective for EE2 degradation. Subsequently, purification of a
synthetic wastewater containing EE2 will be tested in an external MBR with the
acclimated AS. External MBR configuration has been selected because it results
in a more effective biomass, and fouling is easier to control. Compared to
immersed MBRs, floc size is smaller in external MBRs, providing a greater
exposed surface area. To limit fouling during purification experiments,
operational MBR conditions were optimized beforehand; hydrodynamics
parameters and flux were adjusted. Acclimation of nitrifying AS from municipal
WWTPs was developed in an 80 L immersed MBR with a SRT of 30 days. An
immersed MBR provides a less harsh environment for AS acclimation because
the bacteria are not recycled through a pump (as is the case for external MBRs).
Autotrophic characteristics of the biomass required a culture media composed of
NaHCO3 (inorganic carbon source), (NH4)2SO4 (energy and nitrogen source)
and mineral salt supplements (MgSO4, KH2PO4, CaCl2). The pH was controlled
at 7 by automatic titration with NaHCO3. Biodegradation experiments were
performed after 96 days of acclimation, with EE2 concentrations of 1 mg.L -1 , 500
µg.L -1 and 250 µg.L -1 . Sample analysis is currently underway. Membrane fouling